Flame retardant reinforced polyamide resin composition

ABSTRACT

A flame-retardant reinforced polyamide resin composition comprising (a) a half-aromatic polyamide resin having a hexamethylene adipamide unit and a hexamethylene isophthalamide unit, (b) a melamine polyphosphate and (c) an inorganic reinforcing material, and, if necessary, (d) a polyalkylene polyhydric alcohol and/or a fatty acid ester derivative thereof, (e) a bisamide compound, (f) a metal oxide and/or a molybdate, and (g) a metal salt of a higher fatty acid having 10-25 carbon atoms. According to the composition of the present invention, molding materials can be provided which are very high in flame retardancy even when they are molded into thin-wall moldings, do not generate corrosive hydrogen halide gases during burning and, furthermore, have both excellent electric characteristics and excellent molding processability.

RELATED APPLICATIONS

This application is a continuation-in-part of International PCTapplication No. PCT/JP00/06909, filed Oct. 4, 2000 and designating theUnited States.

TECHNICAL FIELD

The present invention relates to a flame retardant polyamide resincomposition, and particularly to a flame retardant polyamide resincomposition suitably usable for parts such as connectors, breakers,magnetic switches, etc. in the electrical and electronic fields andelectronic parts in the field of automobiles. Furthermore, the presentinvention relates to a flame retardant reinforced polyamide resincomposition which is very high in flame retardancy, does not generatecorrosive hydrogen halide gases at the time of burning and has bothexcellent electric characteristics and excellent molding processability.

BACKGROUND ART

Hitherto, polyamide resins have been used in the fields of automobileparts, mechanical parts, electric and electronic parts, etc. because oftheir excellent mechanical strength, heat resistance, etc. However, inthe recent uses for electric and electronic parts, the level ofrequirement for flame retardancy is increasing, and the flame retardancyis required to be much higher than the self-extinguishing propertieswhich the polyamide resins possess inherently. Therefore, intensiveinvestigations have been conducted on increasing the flame retardancylevel to meet the UL94V-0 standard of Underwriters Laboratories, andgenerally it has been attempted to improve flame retardancy of polyamideresins by adding halogen-based flame-retarding agents or triazine-basedflame-retarding agents to polyamide resins.

For example, there are known the addition of chlorine-substitutedpolycyclic compounds to polyamide resins (JP-A-48-29846), addition ofbromine-based flame-retarding agents such as decabromodiphenyl ether(JP-A-47-7134), addition of brominated polystyrene (JP-A-51-47044,JP-A-4-175371), addition of brominated polyphenylene ether(JP-A-54-116054), addition of brominated cross-linked aromatic polymers(JP-A-63-317552), addition of brominated styrene-maleic anhydridepolymers (JP-A-3-168246), etc. Compositions obtained by adding thesehalogen-based flame-retarding agents to glass fiber-reinforced polyamideresins have high flame retardancy and high stiffness, and, hence, havebeen widely used for electric and electronic parts, especially,connectors mounted on or connected with printed circuit laminates.However, halogen-based flame-retarding agents are believed to generatehighly corrosive hydrogen halide gases and smoke or to generate toxicmaterials at the time of combustion, and because of these environmentalproblems, there is a trend to inhibit the use of plastic productscontaining the halogen-based flame-retarding agents.

Under the circumstances, triazine-based flame-retarding agents free ofhalogen have been noted and various investigations have been made onthese flame-retarding agents. For example, there are well known a methodof using melamine as a flame-retarding agent (JP-B-47-1714), a method ofusing cyanuric acid (JP-A-50-105744), and a method of using melaminecyanurate (JP-A-53-31759). Non-reinforced polyamide resin compositionsobtained by these techniques have a high flame retarding level meetingthe requirements of the UL94V-0 standard, but when these compositionsare reinforced with inorganic reinforcing materials such as glass fibersto enhance their stiffness, the cotton ignition phenomenon occurs at thetime of combustion even if the flame-retarding agents are added in alarge amount, and thus they do not meet the requirements of the UL94V-0standard.

On the other hand, there have been proposed a flame retarding techniquewhich is free from halogen and which uses intumescent typeflame-retarding agents such as melamine phosphate, melaminepyrophosphate and melamine polyphosphate in glass fiber-reinforcedpolyamide resins (JP-A-10-505875), and a technique of adding melaminepolyphosphate to polyamide resins reinforced with inorganic materialsand further using a charring catalyst and/or a char forming agent(WO98/45364). It is known that moldings thereof having a thickness of{fraction (1/16)} inch meet the requirements of the UL94V-0 standard.However, according to these techniques, melamine phosphate-basedflame-retarding agents must be used in large amounts in order thatthin-wall moldings of {fraction (1/32)} inch thick, which are especiallydemanded for uses as connectors of electric and electronic parts, meetthe requirements of the UL94V-0 standard. When the melaminephosphate-based flame-retarding agents are used in large amounts, notonly are the glass fiber-reinforced polyamide resin compositionsseriously deteriorated in mechanical characteristics, but also they areinferior in electric characteristics, particularly, tracking resistancewhich is required for electric parts used under high voltageenvironments. Moreover, when the melamine phosphate-basedflame-retarding agents are used in large amounts, releasability from themold at the time of molding is inferior, and, furthermore, molding for along period of time at high molding temperatures is apt to causecorrosion of the mold. Thus, the compositions are not necessarilysatisfactory as molding materials for electric and electronic parts.

Furthermore, there is disclosed a technique of applying melamine sulfatewhich is an intumescent type flame-retarding agent to glassfiber-reinforced half-aromatic polyamide resins for meeting therequirement of the UL94V-0 standard as thin-wall moldings of {fraction(1/32)} inch thick (JP-A-2000-11951), but this technique also requiresthe addition of the flame-retarding agent in a large amount for theamount of the polyamide resin component, and suffers from the sameproblems as above.

Moreover, as a technique for imparting a high tracking resistance whichmeets the requirement of the UL94V-0 standard as thin-wall moldings of{fraction (1/32)} inch thick, there is proposed a technique of adding amelamine phosphate composite flame-retarding agent and an alkaline earthmetal salt to inorganic material-reinforced polyamide resins(WO00/09606), but moldings obtained by this technique are brittle, andwhen applied to, for example, connectors having complicated shapes,there are problems that the connectors are broken or cracked duringhandling or transportation.

The object of the present invention is to provide a flame retardantreinforced polyamide resin composition which is very high in flameretardancy, does not generate hydrogen halide gases having corrosivenessat the time of combustion and has both excellent electriccharacteristics and excellent molding processability.

DISCLOSURE OF INVENTION

As a result of intensive research conducted by the inventors, it hasbeen found that the above object can be attained by using ahalf-aromatic polyamide resin having a specific structure as a polyamideresin in a system comprising a combination of an inorganic reinforcingmaterial, a melamine polyphosphate and a polyamide, and thus the presentinvention has been accomplished.

That is, the present invention is directed to a flame retardantreinforced polyamide resin composition comprising (a) 30-70% by weightof a half-aromatic polyamide resin having a hexamethylene adipamide unitand a hexamethylene isophthalamide unit, (b) 10-38% by weight of amelamine polyphosphate and (c) 5-50% by weight of an inorganicreinforcing material.

Furthermore, if necessary, the flame retardant reinforced polyamideresin composition of the present invention may further comprise (d) 0-5%by weight of a polyalkylene polyhydric alcohol and/or a fatty acid esterderivative thereof, (e) 0-5% by weight of a bisamide compound, (f) 0-5%by weight of a metal oxide and/or a molybdate, and (g) 0-5% by weight ofa metal salt of a higher fatty acid having 10-25 carbon atoms inaddition to the above components (a)-(c).

Moreover, in the flame retardant reinforced polyamide resin compositionof the present invention, it is preferred that the ratio of amounts ofthe half-aromatic polyamide resin and the melamine polyphosphate is inthe range of 1.5-3.5.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a schematic view of a mold used for the measurement ofreleasability from the mold in the examples given below.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be specifically explained below.

<Component (a)>

The half-aromatic polyamide resins used in the present invention arepolyamide resins containing a hexamethylene adipamide unit and ahexamethylene isophthalamide unit as main constituting components, andthese half-aromatic polyamide resins include copolymers containing apolyhexamethylene adipamide unit (hereinafter sometimes referred to as“polyamide 66 unit”) and a polyhexamethylene isophthalamide unit(hereinafter sometimes referred to as “polyamide 6I unit”) and polyamidemixtures (mixed polyamides) containing a polyhexamethylene adipamidecomponent (hereinafter sometimes referred to as “polyamide 66component”) and a polyhexamethylene isophthalamide component(hereinafter sometimes referred to as “polyamide 6I component”).

Especially, when a half-aromatic polyamide resin containing 5-30% byweight of a hexamethylene isophthalamide unit is combined with amelamine polyphosphate, high flame retardancy is obtained, which ispreferred.

As the half-aromatic polyamide resins of the present invention,specifically, copolymers comprising 70-95% by weight of a polyamide 66unit and 5-30% by weight of a polyamide 6I unit (polyamides 66/6I) arepreferred because they satisfy heat resistance, appearance of moldings,molding processability, and electric characteristics, and copolymerscomprising 70-90% by weight of a polyamide 66 unit and 10-30% by weightof a polyamide 6I unit are especially preferred because they haveexcellent flame retardancy and superior releasability during molding inaddition to the above characteristics.

Furthermore, mixed polyamides containing 70-95% by weight of a polyamide66 component and 5-30% by weight of a polyamide 6I component are high inheat resistance and are preferred for uses that require solderingresistance.

In addition, terpolymers comprising 60-89% by weight of a polyamide 66unit, a part of which is replaced with other aliphatic polyamide units,5-30% by weight of a polyamide 6I unit and 1-10% by weight of analiphatic polyamide unit other than the polyamide 66 are superior influidity at molding. As these terpolymers, mention may be made of, forexample, terpolymers in which a part of the polyamide 66 unit isreplaced with an aliphatic polyamide unit selected from a polycapramideunit (polyamide 6 unit), polyundecamide unit (polyamide 11 unit),polydodecamide unit (polyamide 12 unit), polyhexamethylene sebacamideunit (polyamide 610 unit) or polyhexamethylene dodecamide unit(polyamide 612 unit), namely, polyamide 66/6I/6, polyamide 66/6I/11,polyamide 66/6I/12, polyamide 66/6I/610, and polyamide 66/6I/612.

Furthermore, the object of the present invention can also be attained byusing mixed polyamides containing 60-89% by weight of a polyamide 66component, 5-30% by weight of a polyamide 6I component and 1-10% byweight of an aliphatic polyamide component other than the polyamide 66component as the half-aromatic polyamide resins of the presentinvention.

When the amount of the polyhexamethylene isophthalamide unit in thecopolymers or that of the polyhexamethylene isophthalamide component inthe mixed polyamides is in the range of 5-30% by weight, a sufficientflame retardation level can be attained without adding theflame-retarding agent in a large amount, and the compositions areexcellent in heat resistance, molding processability and electriccharacteristics.

The aforementioned copolymers may be either random copolymers or blockcopolymers, and these copolymers may contain other aromatic polyamideresins as copolymer components in such a range that the attainment ofthe object of the present invention is not hindered. The mixedpolyamides of the present invention are polyamides obtained by mixingpolyamides comprising two or more components by general methods such asblending, melt kneading, etc. other than a polymerization method. Themolecular weight of the half-aromatic polyamide resins used in thepresent invention is not particularly limited as far as molding isconcerned, but when polyamide resins having a sulfuric acid relativeviscosity of 1.5-3.5 as specified in JIS K6810 are used, fluidity atmolding is good and a high flame retardation level can be maintained,and thus it is preferred to use such polyamide resins.

<Component (b)>

The melamine polyphosphates used in the present invention arerepresented by the following chemical formula: (C₃H₆N₆·HPO₃), (in theformula, n denotes a condensation degree), and mean those which areobtained from reaction products of substantially equimolar melamine andphosphoric acid or polyphosphoric acid. The process for producing themelamine polyphosphates used in the present invention has no speciallimitation. Usually, mention may be made of melamine polyphosphatesobtained by heat condensation of melamine phosphates in a nitrogenatmosphere. The phosphoric acids constituting the melamine phosphatesinclude specifically orthophosphoric acid, phosphorous acid,hypophosphorous acid, metaphosphoric acid, pyrophosphoric acid,triphosphoric acid, tetraphosphoric acid, etc. Especially, melaminepolyphosphates obtained by condensation of adducts of orthophosphoricacid or pyrophosphoric acid with melamine are preferred because they arehigh in the effects as flame-retarding agents. Furthermore, thecondensation degree n of the melamine polyphosphates is preferably morethan 3, especially preferably not less than 5 from the point of heatresistance.

Moreover, the melamine polyphosphates may be equimolar addition salts ofpolyphosphoric acid and melamine, and the polyphosphoric acid whichforms the addition salts with melamine includes chain polyphosphoricacid and cyclic polymetaphosphoric acid which are called condensationphosphoric acids. The condensation degree n of these polyphosphoricacids has no special limitation, and is usually 3-50, but is preferablynot less than 5 from the point of heat resistance of the resultingmelamine polyphosphate addition salts. The melamine polyphosphateaddition salts are powders obtained by making a mixture of melamine andpolyphosphoric acid into, for example, an aqueous slurry, followed bymixing well to form a reaction product in the form of fine particles,then subjecting the slurry to filtration, washing and drying, and, ifnecessary, firing the product, and grinding the resulting solid product.

From the points of mechanical strength and appearance of the moldingsobtained by molding the composition of the present invention, themelamine polyphosphates used for preparation of the composition arepreferably powders having a particle diameter of not more than 100 μm,more preferably not more than 50 μm. Particularly, when powders of0.5-20 μm are used, not only is a high flame retardancy developed, butalso the strength of moldings is considerably increased, and, hence,these are very preferable. The melamine polyphosphates are notnecessarily completely pure, and some unreacted melamine or phosphoricacid or polyphosphoric acid may remain therein. Furthermore, melaminepolyphosphates containing 10-18% by weight of phosphorus atoms areparticularly preferred, because the phenomenon of attachment ofcontaminants to the molds at the time of the molding operation hardlyoccurs.

The melamine polyphosphates act as flame-retarding agents and exert veryhigh retardation effects when used in combination with inorganicreinforcing materials such as glass fibers, as compared withtriazine-based flame-retarding agents a representative of which ismelamine cyanurate. Particularly, when the melamine polyphosphates areadded to copolymers comprising polyamide 66 units and polyamide 6I unitsor mixed polyamides containing polyamide 66 and polyamide 6I,conspicuously high retardation effects are exerted.

<Component (c)>

As the inorganic reinforcing materials used in the present invention,mention may be made of fibrous, particulate, platy or acicular inorganicreinforcing materials such as glass fibers, carbon fibers, potassiumtitanate fibers, gypsum fibers, brass fibers, stainless steel fibers,steel fibers, ceramic fibers, boron whisker fibers, mica, talc, silica,calcium carbonate, kaolin, calcined kaolin, wollastonite, glass beads,glass flakes, titanium oxide, etc. These reinforcing materials may alsobe used in a combination of two or more. Among them, especiallypreferred are glass fibers, wollastonite, talc, calcined kaolin andmica. The glass fibers can be selected from roving of long fiber type,chopped strands and milled fibers of short fiber type, and the like. Theglass fibers are preferably surface treated for polyamides.

<Component (d)>

In the present invention, polyalkylene polyhydric alcohols and fattyacid ester derivatives thereof show action and effect as tenacityimproving agents. The polyalkylene polyhydric alcohols include dihydricalcohols such as polyethylene glycol, polypropylene glycol, polybutyleneglycol, etc., trihydric alcohols such as sorbitan, glycerin, etc., andthe like. The fatty acid ester derivatives of the polyalkylenepolyhydric alcohols include mono-, di- or triester derivatives of theabove polyhydric alcohols with higher fatty acids such as capric acid,lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid,cerotic acid, montanic acid, melissic acid, oleic acid, erucic acid,etc., and the like.

Specific examples of the component (d) are polyethylene glycolmonolaurate, polyethylene glycol monostearate, polyethylene glycolmonoeruate, polyethylene glycol distearate, ethylene glycol distearate,propylene glycol monostearate, polyoxyethylene bisphenol A laurate,pentaerythritol monooleate, pentaerythritol monostearate, sorbitanmonolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitantristearate, sorbitan monooleate, sorbitan trioleate, sorbitandistearate, sorbitan monobehenate, polyoxyethylene sorbitan monolaurate,polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitanmonostearate, polyoxyethylene tristearate, polyoxyethylene sorbitanmonooleate, polyoxyethylene sorbitan trioleate, stearic acidmonoglyceride, palmitic acid monoglyceride, oleic acid monoglyceride,behenic acid monoglyceride, capric acid monoglyceride, stearic aciddiglyceride, palmitic acid diglyceride, oleic acid diglyceride, behenicacid diglyceride, capric acid diglyceride, capric acid triglyceride,etc.

Especially preferred are polyethylene glycol, polypropylene glycol,polybutylene glycol, polyethylene glycol monolaurate, polyethyleneglycol monostearate, polyethylene glycol monoeruate and polyethyleneglycol distearate which exert high action and effect for improvement oftenacity without causing deterioration of flame retardancy and areindustrially easily available.

<Component (e)>

The bisamide compounds in the present invention are obtained through areaction of an acid and a diamine, and exert action and effect asmoldability improving agents for further remarkable improvement ofreleasability at molding without causing deterioration of flameretardancy. Specific examples of the bisamide compounds are saturatedfatty acid bisamides such as methylenebisstearic acid amide,ethylenebiscapric acid amide, ethylenebislauric acid amide,ethylenebisstearic acid amide, ethylenebisisostearic acid amide,ethylenebishydroxystearic acid amide, ethylenebisbehenic acid amide,hexamethylenebisstearic acid amide, hexamethylenebisbehenic acid amide,hexamethylenebishydroxystearic acid amide, etc., unsaturated fatty acidbisamides such as ethylenebisoleic acid amide, hexamethylenebisoleicacid amide, etc., and aromatic bisamides such as m-xylylenebisstearicacid amide, etc. Especially preferred are methylenebisstearic acidamide, ethylenebiscapric acid amide, ethylenebisstearic acid amide,ethylenebisisostearic acid amide, ethylenebisbehenic acid amide,hexamethylenebisstearic acid amide and hexamethylenebisbehenic acidamide which are higher fatty acid bisamides which hardly generate gasesduring molding and cause no mold deposition phenomena.

<Component (f)>

The metal oxides and metal molybdates of the present invention have theaction and effect as metal corrosion inhibitors, particularly, theaction and effect to prevent occurrence of corrosion phenomenon in themold even if molding is carried out for a long period of time underhigh-temperature molding conditions.

The metal oxides include alkaline earth metal oxides such as berylliumoxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide,radium oxide, aluminum oxide, zinc oxide, etc. From the point of notdeteriorating the flame retardancy, beryllium oxide, magnesium oxide,calcium oxide, strontium oxide and barium oxide are preferred, andcalcium oxide is especially preferred.

The molybdates include ammonium molybdate, potassium molybdate, calciummolybdate, sodium molybdate and lithium molybdate, and alkaline earthmetal molybdates which exert high metal corrosion inhibition effect arepreferred, among which calcium molybdate, barium molybdate and strontiummolybdate are especially preferred.

<Component (g)>

The metal salts of higher fatty acids having 10-25 carbon atoms used inthe present invention have an effect as releasability improving agentsat molding and, in addition, an effect to inhibit the mold depositionphenomenon at molding.

Examples of the metal salts of higher fatty acids having 10-25 carbonatoms are sodium salts, lithium salts, calcium salts, magnesium salts,zinc salts, aluminum salts, etc. of higher fatty carboxylic acids suchas lauric acid, myristic acid, palmitic acid, stearic acid, behenicacid, cerotic acid, oleic acid, erucic acid, etc. Preferred are calciumsalts, magnesium salts, zinc salts and aluminum salts of higher fattycarboxylic acids having 10-25 carbon atoms. Metal salts of fatty acidshaving less than 10 carbon atoms are insufficient in the effect toimprove releasability at molding and, besides, insufficient in theeffect to inhibit the bleed-out phenomenon. Moreover, use of the metalsalts of higher fatty acids having more than 25 carbon atoms causesdeterioration of flame retardancy. Of these metal salts of higher fattyacids, metal salts of stearic acid, specifically, calcium stearate,magnesium stearate, zinc stearate, and aluminum stearate are mostpreferred because they do not deteriorate flame retardancy of theresulting polyamide resin compositions, highly improve releasability atmolding, and can inhibit the bleed-out phenomenon.

<Proportion of Each Component>

In the polyamide resin composition of the present invention, it ispreferred that the proportion of the components (a), (b), (c), (d), (e),(f) and (g) is as shown below when the percentage by weight of each ofthe components (a)-(g) is indicated by A, B, C, D, E, F and G% byweight:

30≦A≦70

10≦B≦38

5≦C≦50

0≦D≦5

0≦E≦5

0≦F≦5

0≦G≦5

1.5≦A/B≦3.5

A+B+C+D+E+F+G=100

That is, the proportion of the half-aromatic polyamide resin ispreferably in the range of 30-70% by weight. If it is less than 30% byweight, molding processability and mechanical properties are damaged,and if it is more than 70% by weight, there is the possibility ofdeterioration in flame retardancy and stiffness.

The proportion of the melamine polyphosphates is preferably 10-38% byweight, more preferably 15-35% by weight. If the amount of the melaminepolyphosphates is less than 10% by weight, the flame retarding effect isinsufficient, and if it is more than 38% by weight, there occur problemssuch as generation of decomposition gases at kneading and deposition ofcontaminants on the molds at molding. Furthermore, there are causedserious deterioration of mechanical properties and deterioration in theappearance of moldings.

The ratio A/B of the amounts of the half-aromatic polyamide resin andthe melamine polyphosphate is preferably in the range of 1.5-3.5. WhenA/B is in this range, electric characteristics, particularly, trackingresistance and mechanical strength are improved, and, besides, excellentflame retarding performance can be stably obtained. An especiallypreferable range of A/B is 1.7-2.5.

Similarly, the proportion of the inorganic reinforcing materials ispreferably 5-50% by weight, more preferably 10-40% by weight. If it isless than 5% by weight, development of mechanical strength and stiffnessis not recognized, and if it exceeds 50% by weight, not only is themolding processability at extruding or injection molding considerablydeteriorated, but also the effect to improve properties based on theamount is not recognized.

In the present invention, the polyalkylene polyhydric alcohol and/orfatty acid ester derivative thereof as the component (d) are notnecessarily needed, but when they are added in an amount of preferablyat most 5% by weight, more preferably 0.01-5% by weight with request tothe polyamide resin composition, the mechanical characteristics of theresin composition are improved, particularly, deflection in bending isincreased and molding materials excellent in tenacity can be obtained.If the amount exceeds 5% by weight, not only is the improving effectsaturated, but also gases are generated at molding or silver streaks areapt to occur on the surface of moldings, and if it is less than 0.01% byweight, the effect to improve mechanical characteristics cannot besufficiently exhibited.

The bisamide compound as the component (e) is also not necessarilyneeded in the present invention, but when it is added in the range ofpreferably at most 5% by weight, more preferably 0.01-5% by weight withrequest to the polyamide resin composition, the moldability of the resincomposition can be improved, and it has the effect to enhance thereleasability of moldings from molds, and has a surprising action andeffect to extremely improve the moldability of thin-wall portions. Ifthe amount exceeds 5% by weight, much gas is generated during themolding operation, and if it is less than 0.01% by weight, the effect toimprove the releasability cannot be sufficiently exhibited.

The metal oxide and/or the molybdate as the component (f) are also notnecessarily needed in the present invention, but when it is added in therange of preferably at most 5% by weight, more preferably 0.01-5% byweight with request to the polyamide resin composition, corrosion of themold during high-temperature molding can be inhibited and the phenomenonof mold corrosion is not recognized even after molding for a long periodof time. If the amount exceeds 5% by weight, the flame retardancy issometimes adversely affected, and if it is less than 0.01% by weight,the effect to improve corrosiveness is insufficient.

Furthermore, in the present invention, when the metal salts of higherfatty acids having 10-25 carbon atoms as the component (g) which are notessential are added in an amount of preferably up to 5% by weight, morepreferably 0.01-5% by weight, releasability at molding can be improvedand further the bleed-out phenomenon does not occur. If the amountexceeds 5% by weight, not only the flame retardancy is adverselyaffected, but also gases are generated at molding to cause sometimesdeterioration of processability, and if the amount is less than 0.01% byweight, the effect to improve releasability at molding is insufficient.

<Other Components>

In the present invention, inorganic flame retarding assistants canfurther be added as far as the mechanical properties or moldingprocessability are not adversely affected. Examples of preferred flameretarding assistants are magnesium hydroxide, aluminum hydroxide, zincsulfide, iron oxide, boron oxide, zinc borate, etc.

As far as the object of the present invention is not adversely affected,other components, for example, coloring agents such as pigments anddyes, copper-based heat stabilizers which are general heat stabilizersfor polyamide resins (for example, copper iodide, copper acetate or thelike in combination with potassium iodide or potassium bromide), organicheat resisting agents represented by hindered phenol type oxidativedeterioration inhibitors, weathering resistance improving agents,nucleating agents, plasticizing agents, antistatic agents, etc. can beadded to the flame retardant polyamide resin composition of the presentinvention.

<Process for Production of Polyamide Resin Composition and Uses>

The process for producing the reinforced flame retardant polyamide resincomposition of the present invention has no special limitation, and theprocess may be one which comprises melt kneading the above-mentionedpolyamide resin, melamine polyphosphate and inorganic filler, and, ifnecessary, polyalkylene polyhydric alcohol and/or fatty acid esterthereof, bisamide compound, metal oxide and/or molybdate, metal salt ofhigher fatty acid having 10-25 carbon atoms, etc. by a kneading machinesuch as a usual single-screw or twin-screw extruder or a kneader at atemperature of 200-350° C.

According to a preferred process for production of the composition, atwin-screw extruder provided with side feed openings at two or morepositions is used, and at least the half-aromatic polyamide resin (a) isfed from the feed opening provided at the top position of the twin-screwextruder, and the melamine polyphosphate (b) and the inorganicreinforcing material (c) are fed from any one of the feed openings,followed by kneading them. This process can attain high productivity andis preferred. According to an especially preferred process, a twin-screwextruder having a ratio of the total barrel length L and the barreldiameter D (L/D) of at least 40 and provided with side feed openings attwo or more positions is used, and the polyamide resin is fed from afeed opening (A) provided at the top position of the extruder, themelamine polyphosphate is fed from a side feed opening (B) provided atthe position downstream from ⅓ of the total barrel length, the inorganicreinforcing material is fed from a side feed opening (C) provided at theposition further downstream from the side feed opening (B), and othercomponents are fed from any one of the feed openings, followed by meltkneading them. By employing the above process, flame retardant polyamideresin compositions further excellent in strength and stiffness can beefficiently obtained. An especially preferred process will bespecifically explained below.

As the extruder, preferred is a twin-screw extruder having a ratio ofthe total barrel length L and the barrel diameter D (L/D) of not lessthan 40 and provided with side feed openings at two or more positions.If the L/D is less than 40, the polyamide resin can hardly besufficiently heated before reaching the position of feeding of themelamine polyphosphate and the position of feeding of the inorganicreinforcing material, and, thus, the melamine polyphosphate and theinorganic reinforcing material are sometimes fed while the polyamideresin is in unmolten state or in the state of high melt viscosity. Ifthe melamine polyphosphate and the inorganic reinforcing material arefed to the polyamide resin in this state, decomposition or foamingphenomenon of the melamine polyphosphate is caused by the high shearingforce, and, as a result, it becomes difficult to obtain a compositionhaving stable flame retardancy, or breakage of the inorganic reinforcingmaterial becomes serious, and it becomes difficult to obtain acomposition excellent in strength and stiffness. In order to plasticizethe polyamide resin into the state of sufficiently low melt viscosity byan extruder having a small L/D of less than 40, there are methods ofraising of the heater temperature, generation of heat by shearing forceemploying a screw construction with use of many kneading blocks, etc.However, these methods are low in energetic efficiency or have thepossibility of causing deterioration of the polyamide resin due to thelocal heating of the polyamide resin. Furthermore, the extruder used ispreferably a co-rotating twin-screw extruder from the points of easinessin screw construction, dispersibility of the melamine polyphosphate andinhibition of breakage of the inorganic reinforcing material.Single-screw extruders require longer retention time and largerdistribution of retention time than twin-screw extruders, whichsometimes result in decomposition of the melamine polyphosphate orbreakage of the inorganic reinforcing material. Moreover,counter-rotating twin-screw extruders are greater in shearing forcebetween the screws, and the inorganic reinforcing material is apt to bebroken, and, thus, use of the co-rotating twin-screw extruders ispreferred. The polyamide resin is fed from the feed opening (A) providedat the top position of the twin-screw extruder, and the melaminepolyphosphate and the inorganic reinforcing material are independentlyfed from the feed openings (B) and (C) provided at the positiondownstream from the feed opening (A), but the melamine polyphosphate ispreferably fed from the feed opening (B) positioned downstream from ⅓ ofthe total barrel length. If the feeding position of the melaminepolyphosphate is upstream from ⅓ of the total barrel length, thepolyamide resin is apt to be in solid state or half-molten state at thefeeding position of the melamine polyphosphate, causing application of alarge shearing force to the melamine polyphosphate fed to the extruderto result in decomposition and foaming of the flame-retarding agent,and, sometimes, it becomes difficult to obtain compositions having astable flame retardancy. If the melamine polyphosphate is fed togetherwith the polyamide resin from the feed opening (A) provided at the topposition, the frame-retarding agent is apt to deposit at the feedopening, and for avoiding the deposition, the feeding amount of theflame-retarding agent per unit time must sometimes be reduced.Therefore, extrusion productivity is deteriorated, and furthermore thereis the possibility of the flame-retarding agent being decomposed orfoamed or the polyamide resin being colored because of retention for along time in the extruder. The especially preferred melting state of thepolyamide resin at the feeding position of the melamine polyphosphate issuch that the melt viscosity of the polyamide resin is not higher than200 Pa·s measured at the melting temperature of the polyamide resin atthe feeding position of the melamine polyphosphate under a shear rate of1000/sec. The method for attaining such a melting state of the polyamideresin has no particular limitation, and there is a method of raising thetemperature of the heater on the upstream side than the feeding positionof the melamine polyphosphate within the temperature range of notcausing deterioration of the polyamide resin or a method of providing akneading block at the screw of the extruder and bringing about theshearing heat generation. In addition, it can be attained by properlyadjusting the molecular weight of the polyamide resin used. The meltviscosity of polyamide resin here is a value obtained by conducting ameasurement with a capillary viscometer using two or more orificesdifferent in the ratio of orifice diameter and orifice length and makingcorrection with respect to the tube length. Further, the feed opening(C) for the inorganic reinforcing material is preferably positioneddownstream from the feed opening (B) for the melamine polyphosphate.When the inorganic reinforcing material is fed to the polyamide resin atthe position upstream the feeding of the melamine polyphosphate or theinorganic reinforcing material is fed to the polyamide resin togetherwith the melamine polyphosphate at the same position as for the melaminepolyphosphate, a high shearing force is apt to be applied to theinorganic reinforcing material and the breakage of the inorganicreinforcing material is apt to become serious. More preferred is amethod according to which gas components generated are removed under areduced pressure in the range of −13.3 kPa to −101.08 kPa from a venthole provided at the position further downstream from the feed opening(C) for the inorganic reinforcing material. The generated gas componentshere are water vapor, air and volatile components such as remainingmonomers and additives accompanying during feeding of the polyamideresin, the melamine polyphosphate and the inorganic reinforcingmaterial. If the removal of the generated gas components under reducedpressure is insufficient, the ropes comprising the flame retardantreinforced polyamide resin composition discharged from the extruder arefoamed and readily broken, which sometimes cause problems in production.The screw construction of the twin-screw extruder has no speciallimitations as far as a shearing force enough to plasticize thepolyamide resin is given on the upstream side from the melaminepolyphosphate feeding position, but it is usually preferred to provide aleft-handed screw element at one or more positions on the upstream sidefrom the melamine polyphosphate feeding position. In case they are onthe downstream side from the melamine polyphosphate feeding position, itis preferred to take care not so as to apply too large shearing force tothe melamine polyphosphate or the inorganic reinforcing material.Specifically, it is preferred to optionally dispose usual right-handedscrew elements left-handed screw elements, neutral kneading blocks,blocks comprising right-handed screw elements having notches at theflight portion, etc.

The compositions of the present invention are molded into variousmoldings for electric, electronic and automobile uses such asconnectors, coil bobbins, breakers, electromagnetic switches, holders,plugs, switches, etc. by known methods such as injection molding,extrusion molding, blow molding, etc.

EXAMPLES

The present invention will be explained in more detail by the followingexamples, which do not limit the present invention. Starting materialsand measuring methods used in the examples and comparative examples areshown below.

[Starting Materials]

(A) Polyamide resins

(a-1): Polyamide 66/6I (85/15) copolymer

2.00 Kg of an equimolar salt of adipic acid and hexamethylenediamine,0.35 kg of an equimolar salt of isophthalic acid andhexamethylenediamine, 0.1 kg of adipic acid and 2.5 kg of pure waterwere charged in an autoclave of 5 L, followed by vigorous stirring.After sufficient replacement with nitrogen, the temperature was raisedfrom room temperature to 220° C. over about 1 hour with stirring. Inthis case, the internal pressure of the autoclave reached 1.76 MPa ingauge pressure due to spontaneous pressure of water vapor in theautoclave, and the heating was continued while removing water out of thereaction system so as not to reach a pressure higher than 1.76 MPa.Furthermore, when the internal temperature reached 260° C. after a lapseof 2 hours, the heating was stopped, and the valve of the autoclave wasclosed and the content was cooled to room temperature over about 8hours. After the cooling, the autoclave was opened, and about 2 kg of apolymer was taken out and ground. The resulting ground polymer wascharged in an evaporator of 10 L and subjected to solid phasepolymerization at 200° C. for 10 hours in a nitrogen stream. Thepolyamide (a-1) obtained by the solid phase polymerization had a meltingpoint of 245° C. and a sulfuric acid relative viscosity of 2.38.

(a-2): Polyamide 66/6I (80/20) copolymer

Polyamide (a-2) was prepared in the same manner as in the abovepolymerization example 1, except that 2.00 kg of an equimolar salt ofadipic acid and hexamethylenediamine, 0.50 kg of an equimolar salt ofisophthalic acid and hexamethylenediamine, 0.1 kg of adipic acid and 2.5kg of pure water were used as the starting materials. The resultingpolyamide (a-2) had a melting point of 239° C. and a sulfuric acidrelative viscosity of 2.41.

(a-3): Polyamide 66/6I (65/35) copolymer

Polyamide (a-3) was prepared in the same manner as in the polymerizationexample 1, except that 1.67 kg of an equimolar salt of adipic acid andhexamethylenediamine, 0.88 kg of an equimolar salt of isophthalic acidand hexamethylenediamine, 0.1 kg of adipic acid and 2.5 kg of pure waterwere used as the starting materials. The resulting polyamide (a-3) had amelting point of 219° C. and a sulfuric acid relative viscosity of 2.45.

(a-4): Polyamide 6T/6I (40/60) copolymer

0.67 Kg of an equimolar salt of terephthalic acid andhexamethylenediamine, 1.0 kg of an equimolar salt of isophthalic acidand hexamethylenediamine, 0.05 kg of adipic acid and 2.5 kg of purewater were charged in an autoclave of 5 L, followed by vigorousstirring. After sufficient replacement with nitrogen, the temperaturewas raised from room temperature to 220° C. over about 1 hour withstirring. In this case, the internal pressure of the autoclave reached1.76 MPa in gauge pressure due to the spontaneous pressure of watervapor in the autoclave, and the heating was continued while removingwater out of the reaction system so as not to reach a pressure higherthan 1.76 MPa. Furthermore, when the internal temperature reached 270°C. after a lapse of 2.5 hours, the heating was stopped, and the valve ofthe autoclave was closed and the content was cooled to room temperatureover about 9 hours. After the cooling, the autoclave was opened, andabout 1.5 kg of a polymer was taken out and ground. The resulting groundpolymer was charged in an evaporator of 10 L and subjected to solidphase polymerization at 200° C. for 10 hours in a nitrogen stream. Thepolyamide (a-4) obtained by the solid phase polymerization had a meltingpoint of 255° C. and a sulfuric acid relative viscosity of 2.28.

(a-5): Polyamide 66

Trade name Leona 1300 manufactured by Asahi Kasei Kogyo K. K.

(a-6): Polyamide 6

Trade name SF1013A manufactured by Ube Industries, Ltd.

(B) Flame-retarding agents

(b-1): Melamine polyphosphate

Trade name Apinon MPP-A manufactured by Sanwa Chemical Co., Ltd.

(b-2): Melamine phosphate

Trade name Apinon P-7202 manufactured by Sanwa Chemical Co., Ltd.

(C) Inorganic reinforcing materials

(c-1): Glass fibers

Trade name CS03JA FT756 manufactured by Asahi Fiber Glass Co., Ltd.(average fiber diameter 10 μm)

(D) Polyhydric alcohols, polyhydric alcohol esters

(d-1): Polyethylene glycol

Trade name MACROGOL 400 manufactured by Sanyo Kasei Co., Ltd.

(d-2): Polyethylene glycol monolaurate

Trade name EMANON 1112 manufactured by Kao Co., Ltd.

(d-3): Polyethylene glycol monostearate

Trade name EMANON 3199 manufactured by Kao Co., Ltd.

(d-4): Polyethylene glycol distearate Trade name EMANON 3299manufactured by Kao Co., Ltd.

(d-5): Pentaerythritol monostearate

Trade name EXCEPARL PE-MS manufactured by Kao Co., Ltd.

(d-6): Pentaerythritol

Reagent for chemistry manufactured by Katayama Kagaku Kogyo Co., Ltd.

(E) Amide compounds

(e-1): Ethylenebisstearic acid amide

Trade name SLIPAX E manufactured by Nippon Kasei Co., Ltd.

(e-2): Ethylenebislauric acid amide

Trade name SLIPAX L manufactured by Nippon Kasei Co., Ltd.

(e-3): Stearic acid amide

Trade name DIAMID 200 manufactured by Nippon Kasei Co., Ltd.

(F) Metal oxides, metal salts

(f-1): Calcium oxide

First grade reagent manufactured by Katayama Kagaku Kogyo Co., Ltd.

(f-2): Magnesium oxide

First grade reagent manufactured by Katayama Kagaku Kogyo Co., Ltd.

(f-3): Calcium molybdate

First grade reagent manufactured by Katayama Kagaku Kogyo Co., Ltd.

(G) Metal salts of higher fatty acids, esters of higher fatty acids

(g-1): Calcium stearate

Trade name SC-100 manufactured by Sakai Kagaku Kogyo Co., Ltd.

(g-2): Aluminum stearate

Trade name SA-100 manufactured by Sakai Kagaku Kogyo Co., Ltd.

(g-3): Sodium caprylate

First grade reagent manufactured by Wako Jun-yaku Co., Ltd.

(g-4): Sodium montanate

Trade name Licomont Cav102 manufactured by Clariant Japan Co., Ltd.

(g-5): Stearyl stearate

Trade name UNISTAR M-9676 manufactured by Nippon Oil & Fats Co., Ltd.

[Measuring Methods]

(1) Flame retardancy of thin-wall moldings:

This was measured in accordance with the method of UL94 (a standardspecified by Underwriters Laboratories Inc. of U.S.A.). The thickness oftest pieces was {fraction (1/16)} inch and {fraction (1/32)} inch, andthe test pieces were molded by an injection molding machine (IS50EPmanufactured by Toshiba Machine Co., Ltd.).

(2) Sulfuric acid relative viscosity:

A relative viscosity in 98% sulfuric acid was measured in accordancewith JIS K6810.

(3) Mechanical characteristics:

A bend test piece (3 mm thick) of ASTM D790 was molded using aninjection molding machine (IS50EP manufactured by Toshiba Machine Co.,Ltd.) and subjected to a bend test in accordance with ASTM D790 toobtain bending strength, bending modulus and amount of deflection inbending.

(4) Tracking resistance (CTI):

A flat plate test piece of 130 mm×130 mm×3 mm (thickness) was moldedunder the conditions of a resin temperature of 280° C. and a moldtemperature of 80° C. using an injection molding machine (IS150manufactured by Toshiba Machine Co., Ltd.). The resulting test piece wasset in a tracking resistance testing machine Model HAT-500-3manufactured by Hitachi Chemical Co., Ltd., and a droplet of a 0.1%aqueous ammonium chloride solution was dropped every 30 seconds under avoltage of 100-600 V and a maximum voltage under which the test piecewas not ruptured with no tracking by the dropping of 50 droplets wasobtained in accordance with IEC Publication 112 standard. The higher theobtained voltage, the better the tracking resistance.

(5) Releasability:

Molding was carried out using a mold provided with the releasing forcemeasuring device shown in FIG. 1 by an injection molding machine (FN3000manufactured by Nissei Jushi Co., Ltd.) under the conditions of acylinder temperature of 280° C., a mold temperature of 80° C., and aninjection pressure of 39.2 MPa, and an ejection force for ejecting amolding from the mold was measured. The smaller the ejection force, thebetter the releasability. In the mold shown in FIG. 1, 1 indicates asprue runner, 2 indicates a cup-shaped molding, 3 indicates an ejectorpin, 4 indicates an ejector plate, 5 indicates a pressure sensor, 6indicates an ejector rod, and 7 indicates a releasing force recorder.

(6) Corrosion of mold metal:

50 Grams of a glass fiber-reinforced polyamide resin pellet and a testpiece of 1 cm×2 cm×0.5 cm (thickness) comprising a tool steel alloy fora mold (SKD11) were put in a pressure container made of stainless steelwhich had a Teflon-coated inner surface and heated at a temperature of280° C. for 5 hours in a constant temperature oil bath, followed bycooling, and the resin component molten and solidified on the metal testpiece was ground and removed. Then, the surface of the test piece wasobserved by a metallurgical microscope. The degree of corrosion wasranked as follows.

x: Corrosion occurred on the whole surface.

Δ: Light pitting occurred.

◯: Substantially no corrosion was seen.

(7) Bleeding:

A molding was left to stand for 240 hours in a thermo-hygrostat adjustedto a temperature of 60° C. and a relative humidity of 95%, andthereafter the bleeding matters precipitated on the surface of themolding was visually observed. The degree of bleeding was judged by thefollowing criteria.

◯: No bleeding matters were observed on the surface of the molding.

x: Bleeding matters were seen on the surface of the molding.

(8) Resin temperature at the feeding position of melamine polyphosphateflame-retarding agent:

This was measured by a thermocouple built in the barrel.

(9) Melt viscosity of the resin at the feeding position of melaminepolyphosphate flame-retarding agent:

A melt shear viscosity was measured at a shear rate of 1000/sec and atthe resin temperature measured in the above (8) using a twin capillaryrheometer RH7-2 manufactured by ROSAND Co., Ltd. In this case, twoorifices of 1.0 mm in die diameter, 180° in die inlet angle, and 16 and0.25 in the ratio of orifice length and orifice diameter were used, andcorrection with respect to the tube length was made to obtain a meltviscosity.

Example 1

In order to obtain a composition comprising 49% by weight of thepolyamide resin (a-1), 26% by weight of the flame-retarding agent (b-1)and 25% by weight of the glass fiber (c-1), the polyamide (a-1) and theflame-retarding agent (b-1) were top-fed and the glass fiber (c-1) wasside-fed from a feed opening provided at the position of 0.68 of thetotal length of the extruder, and these were kneaded and taken out inthe form of a strand using a co-rotating twin-screw extruder (TEM35manufactured by Toshiba Machine Co., Ltd.) having an L/D of 47 under theconditions of a cylinder preset temperature of 260° C., a screw rotationrate of 200 rpm, a vent pressure-reduction degree of −53.2 kPa, and athroughput rate of 30 kg/hr. After cooling, the strands were granulatedby a cutter to obtain pellets of polyamide resin composition. Testpieces were molded from the resulting pellets and the variouscharacteristics were determined by the above-mentioned measuringmethods. The results are shown in Table 1.

Example 2

Pellets were obtained in the same manner as in Example 1, except that(a-2) was used as the polyamide resin. Test pieces were molded from theresulting pellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 1.

Example 3

Pellets were obtained in the same manner as in Example 1, except that(a-3) was used as the polyamide resin. Test pieces were molded from theresulting pellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 1.

Comparative Example 1

Pellets were obtained in the same manner as in Example 1, except that(a-4) was used as the polyamide resin. Test pieces were molded from theresulting pellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 1.

Comparative Example 2

Pellets were obtained in the same manner as in Example 1, except that(a-5) was used as the polyamide resin. Test pieces were molded from theresulting pellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 1.

Comparative Example 3

Pellets were obtained in the same manner as in Example 1, except that(a-6) was used as the polyamide resin. Test pieces were molded from theresulting pellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 1.

Comparative Example 4

Pellets were obtained in the same manner as in Example 1, except that(b-2) was used as the flame-retarding agent. Test pieces were moldedfrom the resulting pellets and the various characteristics weredetermined by the above-mentioned measuring methods. The results areshown in Table 1.

As can be seen from the results of Examples 1-3 and Comparative Examples1-4, all of characteristics of thin-wall flame retardancy, electriccharacteristics and moldability can be satisfied, only when thehalf-aromatic polyamide containing hexamethylene phthalamide unit andthe melamine polyphosphate in specific amounts are used in combination.

Examples 4-5 and Comparative Examples 5-6

Pellets were obtained in the same manner as in Example 1, except thatamounts of the polyamide resin (a-2), the flame-retarding agent (b-1)and the glass fiber (c-1) were as shown in Table 1. Test pieces weremolded from the resulting pellets and the various characteristics weredetermined by the above-mentioned measuring methods. The results areshown in Table 1.

TABLE 1 Example Example Example Comparative Comparative ComparativeComparative Example Example Comparative Comparative 1 2 3 Example 1Example 2 Example 3 Example 4 4 5 Example 5 Example 6 Composition (a)Polyamide resin Kind a-1 a-2 a-3 a-4 a-5 a-6 a-1 a-2 a-2 a-52 a-2 Amount49.0 49.0 49.0 49.0 49.0 49.0 49.0 58.0 41.0 51.0 35.0 (wt %) (b)Flame-retarding Kind b-1 b-1 b-1 b-1 b-1 b-1 b-2 b-1 b-1 b-1 b-1 agentAmount 26.0 26.0 26.0 26.0 26.0 26.0 26.0 32.0 19.0 9.0 40.0 (wt %) (c)Glass fiber Kind c-1 c-1 c-1 c-1 c-1 c-1 c-1 c-1 c-1 c-1 c-1 Amount 25.025.0 25.0 25.0 25.0 25.0 25.0 10.0 40.0 40.0 25.0 (wt %) (a)/(b) mixingratio  1.9  1.9  1.9  1.9  1.9  1.9  1.9  1.8  2.2  5.7  0.9Characteristics Flame-retardancy {fraction (1/32)} inch V-0 V-0 V-0 V-2V-1 V-2 V-1 V-0 V-0 V-2 V-0 (UL94 rank) {fraction (1/16)} inch V-0 V-0V-0 V-1 V-0 V-1 V-0 V-0 V-0 V-2 V-0 Bending strength (MPa) 241   238  221   231   243   238   240   184   275   293   179  Bending modulus(GPa) 10.4 10.6 10.1 10.7  9.8  9.6 10.3  7.5 14.3 13.6 11.3 Deflectionin bending (mm)  3.6  3.5  3.3  3.2  3.7  3.8  3.1  3.2  4.3  5.5  2.8CTI (V) 350   350   275   275   350   350   350   325   475   500  250   Releasability (N) 28.0 28.8 35.2 39.8 28.5 32.4 28.5 29.6 25.528.4 33.6 (ejection force) Corrosion of mold Δ Δ — — — — X Δ Δ — —

Example 6

In order to obtain a composition comprising 47.5% by weight of thepolyamide resin (a-2), 26% by weight of the flame-retarding agent (b-1),25% by weight of the glass fiber (c-1) and 1.5% by weight of thepolyhydric alcohol (d-1), the polyamide (a-2), the flame-retarding agent(b-1) and the polyhydric alcohol (d-1) were top-fed and the glass fiber(c-1) was side-fed from a feed opening provided at the position of 0.68of the total length of the extruder, and these were kneaded and takenout in the form of a strand using a co-rotating twin-screw extruder(TEM35 manufactured by Toshiba Machine Co., Ltd.) having an L/D of 47under the conditions of a cylinder preset temperature of 260° C., ascrew rotation rate of 200 rpm, a vent pressure-reduction degree of−53.2 kPa and a throughput rate of 30 kg/hr. After cooling, the strandswere granulated by a cutter to obtain pellets of polyamide resincomposition. Test pieces were molded from the resulting pellets and thevarious characteristics were determined by the above-mentioned measuringmethods. The results are shown in Table 2.

Examples 7-10

Pellets were obtained in the same manner as in Example 6, except thatpolyhydric alcohol ester derivatives (d-2), (d-3), (d-4) and (d-5) wereused in place of the polyhydric alcohol (d-1). Test pieces were moldedfrom the resulting pellets and the various characteristics weredetermined by the above-mentioned measuring methods. The results areshown in Table 2.

Example 11

Pellets were obtained in the same manner as in Example 6, except thatthe polyhydric alcohol (d-6) was used in place of the polyhydric alcohol(d-1). Test pieces were molded from the resulting pellets and thevarious characteristics were determined by the above-mentioned measuringmethods. The results are shown in Table 2.

Examples 12-14

Pellets were obtained in the same manner as in Example 6, except thatamounts of the polyamide resin (a-2), the flame-retarding agent (b-1),the glass fiber (c-1) and the polyhydric alcohol ester derivative (d-2)were as shown in Table 2. Test pieces were molded from the resultingpellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 2.

TABLE 2 Example Exam- Example Exam- Example Exam- Example Exam- Example6 ple 7 8 ple 9 10 ple 11 12 ple 13 14 Composition (a) Polyamide resinKind a-2 a-2 a-2 a-2 a-2 a-2 a-2 a-2 a-2 Amount 47.5 47.5 47.5 47.5 47.547.5 48.5 46.0 43.0 (wt %) (b) Flame-retarding Kind b-1 b-1 b-1 b-1 b-1b-1 b-1 b-1 b-1 agent Amount 26.0 26.0 26.0 26.0 26.0 26.0 26.0 26.026.0 (wt %) (c) Glass fiber Kind c-1 c-1 c-1 c-1 c-1 c-1 c-1 c-1 c-1Amount 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 (wt %) (d)Polyhydric alcohol Kind d-1 d-2 d-3 d-4 d-5 d-6 d-2 d-2 d-2 or esterderiva- Amount  1.5  1.5  1.5  1.5  1.5  1.5  0.5  3.0  6   tive thereof(wt %) (a)/(b) mixing ratio  1.8  1.8  1.8  1.8  1.8  1.8  1.9  1.8  1.7Charateristics Flame-retardancy {fraction (1/32)} inch V-0 V-0 V-0 V-0V-0 V-0 V-0 V-0 V-0 (UL94 rank) {fraction (1/16 )} inch V-0 V-0 V-0 V-0V-0 V-0 V-0 V-0 V-0 Bending strength (MPa) 238   236   237   238   233  234   234   238   231   Bending modulus (GPa) 10.6 10.5 10.2 10.4 10.510.5 10.6 10.7 10.1 Deflection in bending (mm)  4.1  4.6  4.6  4.5  3.9 3.6  4.1  4.7  4.8 CTI (V) 350   350   350   350   350   350   350  350   350   Releasability (N) 25.5 25.3 25.8 25.3 26.6 26.2 25.9 25.324.4 (ejection force) (much gas) Corrosion of mold Δ Δ Δ Δ — — — Δ Δ

Example 15

In order to obtain a composition comprising 48.9% by weight of thepolyamide resin (a-2), 26% by weight of the flame-retarding agent (b-1),25% by weight of the glass fiber (c-1) and 0.1% by weight of thebisamide compound (e-1), the polyamide (a-2), the flame-retarding agent(b-1) and the bisamide compound (e-1) were top-fed and the glass fiber(c-1) was side-fed from a feed opening provided at the position of 0.68of the total length of the extruder, and these were kneaded and takenout in the form of a strand using a co-rotating twin-screw extruder(TEM35 manufactured by Toshiba Machine Co., Ltd.) having an L/D of 47under the conditions of a cylinder preset temperature of 260° C., ascrew rotation rate of 200 rpm, a vent pressure-reduction degree of−53.2 kPa and a throughput rate of 30 kg/hr. After cooling, the strandswere granulated by a cutter to obtain pellets of polyamide resincomposition. Test pieces were molded from the resulting pellets and thevarious characteristics were determined by the above-mentioned measuringmethods. The results are shown in Table 3.

Examples 16-18

Pellets were obtained in the same manner as in Example 15, except thatamounts of the polyamide resin (a-2), the flame-retarding agent (b-1),the glass fiber (c-1) and the bisamide compound (e-1) were as shown inTable 3. Test pieces were molded from the resulting pellets and thevarious characteristics were determined by the above-mentioned measuringmethods. The results are shown in Table 3.

Example 19

In order to obtain a composition comprising 47.9% by weight of thepolyamide resin (a-2), 26% by weight of the flame-retarding agent (b-1),25% by weight of the glass fiber (c-1), 1.0% by weight of the polyhydricalcohol ester derivative (d-2) and 0.1% by weight of the bisamidecompound (e-2), the polyamide (a-2), the flame-retarding agent (b-1),the polyhydric alcohol ester derivative and the bisamide compound (e-2)were top-fed and the glass fiber (c-1) was side-fed from a feed openingprovided at the position of 0.68 of the total length of the extruder,and these were kneaded and taken out in the form of a strand using aco-rotating twin-screw extruder (TEM35 manufactured by Toshiba MachineCo., Ltd.) having an L/D of 47 under the conditions of a cylinder presettemperature of 260° C., a screw rotation rate of 200 rpm, a ventpressure-reduction degree of −53.2 kPa and a throughput rate of 30kg/hr. After cooling, the strands were granulated by a cutter to obtainpellets of polyamide resin composition. Test pieces were molded from theresulting pellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 3.

Example 20

Pellets were obtained in the same manner as in Example 19, except thatamounts of the polyamide resin (a-2), the flame-retarding agent (b-1),the glass fiber (c-1), the polyhydric alcohol ester derivative (d-3) andthe bisamide compound (e-2) were as shown in Table 3. Test pieces weremolded from the resulting pellets and the various characteristics weredetermined by the above-mentioned measuring methods. The results areshown in Table 3.

Example 21

Pellets were obtained in the same manner as in Example 16, except thatamide compound (e-3) was used in place of the bisamide compound (e-1).Test pieces were molded from the resulting pellets and the variouscharacteristics were determined by the above-mentioned measuringmethods. The results are shown in Table 3.

Example 22

In order to obtain a composition comprising 47.5% by weight of thepolyamide resin (a-2), 26% by weight of the flame-retarding agent (b-1),25% by weight of the glass fiber (c-1), 0.5% by weight of the bisamidecompound (e-1) and 1.0% by weight of the metal oxide (f-1), thepolyamide (a-2), the flame-retarding agent (b-1), the bisamide compound(e-1) and the metal oxide (f-1) were top-fed and the glass fiber (c-1)was side-fed from a feed opening provided at the position of 0.68 of thetotal length of the extruder, and these were kneaded and taken out inthe form of a strand using a co-rotating twin-screw extruder (TEM35manufactured by Toshiba Machine Co., Ltd.) having an L/D of 47 under theconditions of a cylinder preset temperature of 260° C., a screw rotationrate of 200 rpm, a vent pressure-reduction degree of −53.2 kPa and athroughput rate of 30 kg/hr. After cooling, the strands were granulatedby a cutter to obtain pellets of polyamide resin composition. Testpieces were molded from the resulting pellets and the variouscharacteristics were determined by the above-mentioned measuringmethods. The results are shown in Table 3.

Example 23

Pellets were obtained in the same manner as in Example 22, except thatthe metal oxide (f-2) was used in place of the metal oxide (f-1). Testpieces were molded from the resulting pellets and the variouscharacteristics were determined by the above-mentioned measuringmethods. The results are shown in Table 3.

Example 24

In order to obtain a composition comprising 46.5% by weight of thepolyamide resin (a-2), 26% by weight of the flame-retarding agent (b-1),25% by weight of the glass fiber (c-1), 1.0% by weight of the polyhydricalcohol ester derivative (d-2), 0.5% by weight of the bisamide compound(e-1) and 1% by weight of the metal salt (f-3), the polyamide (a-2), theflame-retarding agent (b-1), the polyhydric alcohol ester derivative(d-2), the bisamide compound (e-1) and the metal salt (f-3) were top-fedand the glass fiber (c-1) was side-fed from a feed opening provided atthe position of 0.68 of the total length of the extruder, and these werekneaded and taken out in the form of a strand using a co-rotatingtwin-screw extruder (TEM35 manufactured by Toshiba Machine Co., Ltd.)having an L/D of 47 under the conditions of a cylinder presettemperature of 260° C., a screw rotation rate of 200 rpm, a ventpressure-reduction degree of −53.2 kPa and a throughput rate of 30kg/hr. After cooling, the strands were granulated by a cutter to obtainpellets of polyamide resin composition. Test pieces were molded from theresulting pellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 3.

TABLE 3 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple15 ple 16 ple 17 ple 18 ple 19 ple 20 ple 21 ple 22 ple 23 ple 24Composition (a) Polyamide resin Kind a-2 a-2 a-2 a-2 a-2 a-2 a-2 a-2 a-2a-2 Amount 48.9 48.5 48.0 43.0 47.9 47.5 48.5 47.5 47.5 46.5 (wt %) (b)Flame-retarding Kind b-1 b-1 b-1 b-1 b-1 b-1 b-1 b-1 b-1 b-1 agentAmount 26.0 26.0 26.0 26.0 26.0 26.0 26.0 26.0 26.0 26.0 (wt %) (c)Glass fiber Kind c-1 c-1 c-1 c-1 c-1 c-1 c-1 c-1 c-1 c-1 Amount 25.025.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 (wt %) (d) Ester derivativeof Kind — — — — d-2 d-3 — — — d-2 polyhydric alcohol Amount — — — — 1.01.0 — — — 1.0 (wt %) (e) Amide compound Kind e-1 e-1 e-1 e-1 e-1 e-1 e-1e-1 e-1 e-1 Amount 0.1 0.5 1.0 6.0 0.1 0.5 0.5 0.5 0.5 0.5 (wt %) (f)Oxide or metai salt Kind — — — — — — — f-1 f-2 f-3 Amount — — — — — — —1.0 1.0 1.0 (wt %) (a) / (b) mixing ratio 1.9 1.9 1.8 1.7 1.8 1.8 1.91.8 1.8 1.8 Characteristics Flame-retardancy {fraction (1/32)} inch V-0V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 (UL94 rank) {fraction (1/16)} inchV-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 Bending strength (MPa) 238 236232 229 239 236 234 235 235 235 Bending modulus (GPa) 10.6 10.5 10.210.4 10.5 10.5 10.6 10.7 10.7 10.7 Deflection in bending (mm) 3.5 3.53.5 3.3 4.3 4.6 3.4 3.4 3.4 4.6 CTI (V) 350 350 350 350 350 350 350 375375 375 Releasability (N) 26.0 23.5 21.3 22.0 26.6 24.1 29.1 22.4 24.423.8 (ejection force) (much gas) Corrosion of mold Δ Δ — — — Δ Δ ◯ ◯ ◯

Example 25

In order to obtain a composition comprising 49.8% by weight of thepolyamide resin (a-1), 25.0% by weight of the flame-retarding agent(b-1), 25% by weight of the glass fiber (c-1), and 0.2% by weight of themetal salt of higher fatty acid (g-1), the polyamide (a-1), theflame-retarding agent (b-1) and the metal salt of higher fatty acid(g-1) were top-fed and the glass fiber (c-1) was side-fed from a feedopening provided at the position of 0.68 of the total length of theextruder, and these were kneaded and taken out in the form of a strandusing a co-rotating twin-screw extruder (TEM35 manufactured by ToshibaMachine Co., Ltd.) having an L/D of 47 under the conditions of acylinder preset temperature of 240° C., a screw rotation rate of 100rpm, a vent pressure-reduction degree of −53.2 kPa and a throughput rateof 30 kg/hr. After cooling, the strands were granulated by a cutter toobtain pellets of polyamide resin composition. Test pieces were moldedfrom the resulting pellets and the various characteristics weredetermined by the above-mentioned measuring methods. The results areshown in Table 4.

Example 26

Pellets were obtained in the same manner as in Example 25, except that(a-2) was used as the polyamide resin. Test pieces were molded from theresulting pellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 4.

Example 27

Pellets were obtained in the same manner as in Example 25, except that(a-3) was used as the polyamide resin. Test pieces were molded from theresulting pellets and the various characteristics were determined by theabove-mentioned measuring methods. The results are shown in Table 4.

Example 28

In order to obtain a composition comprising 49.0% by weight of thepolyamide resin (a-2), 25.0% by weight of the flame-retarding agent(b-1), 25.0% by weight of the glass fiber (c-1), and 1.0% by weight ofthe metal salt of higher fatty acid (g-1), the polyamide (a-2), theflame-retarding agent (b-1) and the metal salt of higher fatty acid(g-1) were top-fed and the glass fiber (c-1) was side-fed from a feedopening provided at the position of 0.68 of the total length of theextruder, and these were kneaded and taken out in the form of a strandusing a co-rotating twin-screw extruder (TEM35 manufactured by ToshibaMachine Co., Ltd.) having an L/D of 47 under the conditions of acylinder preset temperature of 240° C., a screw rotation rate of 100rpm, a vent pressure-reduction degree of −53.2 kPa and a throughput rateof 30 kg/hr. After cooling, the strands were granulated by a cutter toobtain pellets of polyamide resin composition. Various characteristicsof the resulting pellets were determined by the above-mentionedmeasuring methods. The results are shown in Table 4.

Example 29

Pellets were obtained in the same manner as in Example 28, except that(g-2) was used as the metal salt of higher fatty acid, and the amountswere as shown in Table 4, and various characteristics were determined.The results are shown in Table 4.

Example 30

Pellets were obtained in the same manner as in Example 28, except thatthe amount of the metal salt of higher fatty acid was 0, and the amountsof the polyamide resin (a-2), the flame-retarding agent (b-1) and theglass fiber (c-1) were as shown in Table 4, and various characteristicswere determined. The results are shown in Table 4.

Example 31

Pellets were obtained in the same manner as in Example 28, except that(g-3) was used as the metal salt of higher fatty acid, and the amountswere as shown in Table 4, and various characteristics were determined.The results are shown in Table 4.

Example 32

Pellets were obtained in the same manner as in Example 28, except that(g-4) was used as the metal salt of higher fatty acid, and the amountswere as shown in Table 4, and various characteristics were determined.The results are shown in Table 4.

Example 33

Pellets were obtained in the same manner as in Example 28, except that(g-5) was used as the metal salt of higher fatty acid, and the amountswere as shown in Table 4, and various characteristics were determined.The results are shown in Table 4.

TABLE 4 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 25 ple26 ple 27 ple 28 ple 29 ple 30 ple 31 ple 32 ple 33 Composition (a)Polyamide resin Kind a-1 a-2 a-3 a-2 a-2 a-2 a-2 a-2 a-2 Amount 49.849.8 49.8 49.0 49.8 50.0 49.8 49.8 49.8 (wt %) (b) Flame-retarding Kindb-1 b-1 b-1 b-1 b-1 b-1 b-1 b-1 b-1 agent Amount 25.0 25.0 25.0 25.025.0 25.0 25.0 25.0 25.0 (wt %) (c) Glass fiber Kind c-1 c-1 c-1 c-1 c-1c-1 c-1 c-1 c-1 Amount 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 (wt%) (g) Metal salt of Kind g-1 g-1 g-1 g-1 g-2 — g-3 g-4 g-5 higher fattyacid Amount  0.2  0.2  0.2  1.0  0.2 0    0.2  0.2  0.2 (wt %)Characteristics Thin-wall Rank — V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-1 V-1flame Average second  1.2  0.9  0.7  3.2  1.1  0.7  0.9  6.8 15.8retardancy buring time UL94 Ignition of — No No No No No No No No Noinch) cotton (1/32 Bending strength (MPa) 241   238   221   232   239  237   238   236   232   Bending modulus (Ga) 10.4 10.6 10.1 10.2 10.510.5 10.4 10.3 10.4 Releasability (N) 28.0 28.8 35.2 24.2 29.8 40.2 38.725.3 21.5 (ejection force) Bleeding — ◯ ◯ ◯ ◯ ◯ x x ◯ ◯

Example 34

Using a co-rotating twin-screw extruder (TEM35 manufactured by ToshibaMachine Co., Ltd.) having an L/D of 47, the polyamide resin (a-1) wastop-fed from a feed opening (A) provided at the top position of theextruder at 29.4 kg/hr using a gravimetric feeder, the flame-retardingagent (b-1) was side-fed from a feed opening (B) provided at theposition of 0.5 of the total length of the extruder (in the case of thehighest upstream being 0 and the lowest downstream being 1) at 15.6kg/hr using a gravimetric feeder, and the glass fiber (c-1) was side-fedfrom a feed opening (C) provided at the position of 0.68 of the totallength of the extruder which was further downstream from the opening (B)at 15.0 kg/hr using a gravimetric feeder, and these were melt kneadedand taken out in the form of a rope under the conditions of a cylinderpreset temperature of 260° C., a screw rotation rate of 200 rpm, a ventpressure-reduction degree of −53.2 kPa and a throughput rate of 60kg/hr. After cooling, the ropes were granulated by a cutter to obtainpellets of polyamide resin composition. The resulting pellets weresubjected to determination of various characteristics by theabove-mentioned measuring methods. The results are shown in Table 5.

Example 35

Pellets were obtained in the same manner as in Example 34, except thatthe vent pressure-reduction degree was 0 kPa, namely, deaeration was notcarried out. The stability of the resulting ropes was somewhat inferiorto that of the ropes in Example 34, but the physical properties and theflame retardancy were good. The results are shown in Table 5.

Example 36

Using a co-rotating twin-screw extruder (TEM35 manufactured by ToshibaMachine Co., Ltd.) having an L/D of 47, the polyamide resin (a-1) andthe flame-retarding agent (b-1) were top-fed from a feed opening (A)provided at the top position of the extruder at 14.7 kg/hr and 7.8kg/hr, respectively, using gravimetric feeders, and the glass fiber(c-1) was side-fed from a feed opening (C) provided at the position of0.68 of the total length of the extruder at 7.5 kg/hr using agravimetric feeder, and these were melt kneaded and taken out in theform of a rope under the conditions of a cylinder preset temperature of260° C., a screw rotation rate of 200 rpm, a vent pressure-reductiondegree of −53.2 kPa and a throughput rate of 30 kg/hr. After cooling,the ropes were granulated by a cutter to obtain pellets of polyamideresin composition. No deposition and blockade phenomena occurred at thefeed opening (A), but the productivity was lower and strength andstiffness of the resulting composition were lower as compared with themethod of Example 34. Moreover, the pellets were colored whitish yellowas compared with those in Example 34. Furthermore, the maximum burningtime was long. The results are shown in Table 5.

TABLE 5 Example 34 Example 35 Example 36 Polyamide resin Kind a-1 a-1a-1 Feeding amount (kg/hr) 29.4 29.4 14.7 Feeding position Note 1) 0 0 0Melamine phosphate-based Kind b-1 b-1 b-1 flame-retarding agent Feedingamount (kg/hr) 15.6 15.6 7.8 Feeding position Note 1) 0.5 0.5 0 Glassfiber Kind c-1 c-1 c-1 Feeding amount (kg/hr) 15.0 15.0 7.5 Feedingposition Note 1) 0.68 0.68 0.68 Melt viscosity of resin at the feedingposition of 85 85 Unmeasurable melamine phosphate-base flame-retardingagent Pa.s Note 2) Degree of pressure reduction cmHg −40 0 −40 Flameretardancy ({fraction (1/32)} Average burning time (sec) 1.5 1.9 4.3inch) Maximum buring time (sec) 4.9 5.5 9.6 UL94 rank VO VO VO Bendingstrength Mpa 240 238 218 Bending modulus Gpa 10.8 10.3 9.8 Deflection inbending mm 4.0 3.8 3.5 Productivity (discharge kg/hr 60 60 30 amount)Stability of ropes times Note 3) 0 1 3 Note 1) The total length ofbarrel is indicated by 1, and the highest upstream side is indicated by0, the middle is indicated by 0.5 and the lowest downstream side isindicated by 1. Note 2) Melt viscosity of polyamide resin measured atresin measured at resin temperature at the feeding position of melaminephosphate-based flame-retarding agent and and at shear rate of 1000/sec.Note 3) The breakage times of ropes per 30 minutes during compounding.

Industrial Applicability

The compositions of the present invention are molding materials whichare very high in flame retardancy even when they are molded intothin-wall moldings, do not generate corrosive hydrogen halide gases whenburning and, furthermore, have both excellent electric characteristicsand excellent molding processability, and can be employed for uses suchas appliance parts, electronic parts, automobile parts, etc.

What is claimed is:
 1. A flame-retardant reinforced polyamide resincomposition comprising (a) 30-70% by weight of a half-aromatic polyamideresin having a polyhexamethylene adipamide unit and a polyhexamethyleneisophthalamide unit, (b) 10-38% by weight of a melamine polyphosphate,(c) 5-50% by weight of an inorganic reinforcing material, (d) 0-5% byweight of a polyalkylene polyhydric alcohol and/or a fatty acid esterderivative thereof, (e) 0-5% by weight of a bisamide compound, (f) 0-5%by weight of a metal oxide and/or a molybdate, and (g) 0-5% by weight ofa metal salt of a higher fatty acid having 10-25 carbon atoms, where theratio of the amounts of the half-aromatic polyamide resin (a) and themelamine polyphosphate (b) in the composition is 1.5-3.5, and thehalf-aromatic polyamide resin (a) is at least one polymer selected fromthe group consisting of (1) a copolymer comprising 70-95% by weight of apolyhexamethylene adipamide unit and 5-30% by weight of apolyhexamethylene isophthalamide unit; (2) a terpolymer comprising60-89% by weight of a polyhexamethylene adipamide unit, 5-30% by weightof a polyhexamethylene isophthalamide unit and 1-10% by weight of analiphatic polyamide unit other than polyhexamethylene adipamide; (3) amixed polyamide containing 70-95% by weight of a polyhexamethyleneadipamide component and 5-30% by weight of a polyhexamethyleneisophthalamide component; and (4) a mixed polyamide containing 60-89% byweight of a polyhexamethylene adipamide component, 5-30% by weight of apolyhexamethylene isophthalamide component and 1-10% by weight of analiphatic polyamide component other than polyhexamethylene adipamide. 2.A flame-retardant reinforced polyamide resin composition according toclaim 1, wherein the amount of the polyalkylene polyhydric alcoholand/or the fatty acid ester derivative thereof (d) is 0.01-5% by weight.3. A flame-retardant reinforced polyamide resin composition according toclaim 2, wherein the polyalkylene polyhydric alcohol is at least onepolyhydric alcohol selected from the group consisting of polyethyleneglycol, polypropylene glycol and polybutylene glycol.
 4. Aflame-retardant reinforced polyamide resin composition according toclaim 2, wherein the fatty acid ester derivative of the polyalkylenepolyhydric alcohol is at least one higher fatty acid ester derivative ofa polyhydric alcohol selected from the group consisting of polyethyleneglycol monolaurate, polyethylene glycol monostearate, polyethyleneglycol monooleate and polyethylene glycol distearate.
 5. Aflame-retardant reinforced polyamide resin composition according toclaim 1, wherein the amount of the bisamide compound (e) is 0.01-5% byweight.
 6. A flame-retardant reinforced polyamide resin compositionaccording to claim 5, wherein the bisamide compound (e) is at least onesaturated fatty acid bisamide selected from the group consisting ofmethylenebisstearic acid amide, ethylenebiscapric acid amide,ethylenebislauric acid amide, ethylenebisstearic acid amide,ethylenebisisostearic acid amide, ethylenebisbehenic acid amide,hexamethylenebisstearic acid amide and hexamethylenebisbehenic acidamide.
 7. A flame-retardant reinforced polyamide resin compositionaccording to claim 1, wherein the amount of the metal oxide and/ormolybdate (f) is 0.01-5% by weight.
 8. A flame-retardant reinforcedpolyamide resin composition according to claim 7, wherein the metaloxide is at least one alkaline earth metal oxide selected from the groupconsisting of beryllium oxide, magnesium oxide, calcium oxide, strontiumoxide and barium oxide.
 9. A flame-retardant reinforced polyamide resincomposition according to claim 7, wherein the molybdate is at least onealkaline earth metal salt of molybdic acid selected from the groupconsisting of calcium molybdate, barium molybdate and strontiummolybdate.
 10. A flame-retardant reinforced polyamide resin compositionaccording to claim 1, wherein the amount of the metal salt of higherfatty acid having 10-25 carbon atoms (g) is 0.01-5% by weight.
 11. Aflame-retardant reinforced polyamide resin composition according toclaim 10, wherein the metal salt of higher fatty acid having 10-25carbon atoms (g) is at least one alkaline earth metal salt of higherfatty acids which is selected from the group consisting of calcium salt,magnesium salt, zinc salt and aluminum salt of lauric acid, myristicacid, palmitic acid, stearic acid, behenic acid, cerotic acid, oleicacid and erucic acid.
 12. A flame-retardant reinforced polyamide resincomposition according to claim 1, wherein the melamine polyphosphate (b)contains 10-18% by weight of phosphorus atoms.
 13. A flame-retardantreinforced polyamide resin composition according to claim 1, wherein themelamine polyphosphate (b) has an average particle diameter of 0.5-20μm.
 14. A flame-retardant reinforced polyamide resin compositionaccording to claim 1, wherein the condensation degree of the melaminepolyphosphate (b) is not less than
 5. 15. A flame-retardant reinforcedpolyamide resin composition according to claim 1, wherein the inorganicreinforcing material (c) is at least one reinforcing material selectedfrom the group consisting of glass fibers, wollastonite, talc, calcinedkaolin and mica.
 16. A method for producing a flame-retardant reinforcedpolyamide resin composition comprising (a) 30-70% by weight of ahalf-aromatic polyamide resin having a polyhexamethylene adipamide unitand a polyhexamethylene isophthalamide unit, (b) 10-381 by weight of amelamine polyphosphate, (c) 5-50% by weight of an inorganic reinforcingmaterial, (d) 0-5% by weight of a polyalkylene polyhydric alcohol and/ora fatty acid ester derivative thereof, (e) 0-5% by weight of a bisamidecompound, (f) 0-5% by weight of a metal oxide and/or a molybdate, and(g) 0-5% by weight of a metal salt of a higher fatty acid having 10-25carbon atoms, where the ratio of the amounts of the half-aromaticpolyamide resin (a) and the melamine polyphosphate (b) in thecomposition is 1.5-3.5, and the half-aromatic polyamide resin (a) is atleast one polymer selected from the group consisting of (1) a copolymercomprising 70-95% by weight of a polyhexamethylene adipamide unit and5-30% by weight of a polyhexamethylene isophthalamide unit; (2) aterpolymer comprising 60-89% by weight of a polyhexamethylene adipamideunit, 5-30% by weight of a polyhexamethylene isophthalamide unit and1-10% by weight of an aliphatic polyamide unit other thanpolyhexamethylene adipamide; (3) a mixed polyamide containing 70-95% byweight of a polyhexamethylene adipamide component and 5-30% by weight ofa polyhexamethylene isophthalamide component; and (4) a mixed polyamidecontaining 60-89% by weight of a polyhexamethylene adipamide component,5-30% by weight of a polyhexamethylene isophthalamide component and1-10% by weight of an aliphatic polyamide component other thanpolyhexamethylene adipamide, said method comprising using a twin-screwextruder provided with side feed openings at two or more positions, andfeeding at least the half-aromatic polyamide resin (a) from the feedopening provided at the top position of the twin-screw extruder, and themelamine polyphosphate (b) and the inorganic reinforcing material (c)from any one of the side feed openings, followed by kneading them.